In general, the refrigerator includes a compressor, a condenser, an expansion valve and an evaporator to perform a cooling cycle, and thus keeps the freshness of food items for a long period of time by cold air generated through such a cooling cycle.
In such a refrigerator, a freezer compartment for preserving food items in a frozen state and a refrigerator compartment for preserving the food items in a refrigerated state are partitioned inside a main body forming external appearance thereof, so that the food items can be stored in either the refrigerator compartment or the freezer compartment according to the storage temperature of the food items.
FIG. 1 shows a configuration of a conventional refrigerator 10 whose refrigerator compartment is provided with a plurality of shelves 11 and a vegetable room 12 to separately store a large amount of food items such as vegetables or fruits therein.
Such a refrigerator keeps the vegetables stored therein at a low temperature by simply controlling the cold air, whereby the freshness of the vegetables can be maintained for a certain period of time. However, in case of preserving them for a long time, the freshness of the vegetables may not be maintained.
The vegetables, which belong to the plant kingdom, respire and transpire even while they are stored in a refrigerator. Therefore, in order to maintain the freshness of the vegetables stored in the refrigerator, it is necessary to suppress the respiration and the transpiration.
Accordingly, the conventional refrigerator can maintain a certain degree of freshness by keeping the vegetables at a low temperature to suppress the respiration and in a high humidity to prevent the transpiration. However, since the chlorophyll contained in the vegetables cannot be prevented from being decomposed, the freshness of the vegetables cannot be maintained due to a decrease in the concentration of chlorophyll contained in the vegetables with the lapse of a certain period of time.